1. Field of the Invention
The present invention relates to a silicon carbide semiconductor device and a method of manufacturing the silicon carbide semiconductor device, in particular, a silicon carbide semiconductor device including a silicon carbide substrate having an impurity region formed therein and a method of manufacturing such a silicon carbide semiconductor device.
2. Description of the Background Art
In recent years, in order to achieve high breakdown voltage, low loss, and utilization of semiconductor devices under a high temperature environment, silicon carbide has begun to be adopted as a material for a semiconductor device. Silicon carbide is a wide band gap semiconductor having a band gap larger than that of silicon, which has been conventionally widely used as a material for semiconductor devices. Hence, by adopting silicon carbide as a material for a semiconductor device, the semiconductor device can have a high breakdown voltage, a reduced on-resistance, and the like. Further, the semiconductor device thus adopting silicon carbide as its material has characteristics less deteriorated even under a high temperature environment than those of a semiconductor device adopting silicon as its material, advantageously.
For example, Japanese Patent Laying-Open No. 8-8210 describes a method of manufacturing a silicon carbide semiconductor element including an electrode making ohmic contact with a silicon carbide substrate. According to the method of manufacturing the silicon carbide semiconductor element, ions are implanted into a surface of the silicon carbide substrate, and then the surface layer is thermally oxidized from the surface up to a depth at which the concentration of the ion species thus implanted has a peak value. An oxide layer, which is formed by the thermal oxidation, is removed and then a metal electrode is formed on the exposed surface. In this way, an electrode having a low contact resistance can be allegedly formed on the surface of the silicon carbide substrate.